A mesoscale convective system developed across southwest North Dakota and moved southeast across parts of northwest and west central South Dakota. The system produced widespread large hail and damaging wind gusts across Perkins, Ziebach, Haakon, and far eastern Pennington Counties. The most substantial damage was reported around Bison, where wind gusts over 80 mph damaged buildings and knocked down many power lines.

Hail in PENNINGTON, SOUTH DAKOTA
From 21-JUL-05 18:40:00 to 21-JUL-05 18:40:00 (MST)
Location: CREIGHTON
Magnitude: 0.75 
Property damage: 0
Crop damage: 0
Reported by: GENERAL PUBLIC

Thunderstorm Wind in PENNINGTON, SOUTH DAKOTA
From 21-JUL-05 18:40:00 to 21-JUL-05 18:40:00 (MST)
Location: CREIGHTON
Magnitude: 52 EG
Property damage: 0
Crop damage: 0
Reported by: GENERAL PUBLIC

Thunderstorm Wind in PERKINS, SOUTH DAKOTA
From 21-JUL-05 16:05:00 to 21-JUL-05 16:05:00 (MST)
Location: SHADEHILL
Magnitude: 61 EG
Property damage: 0
Crop damage: 0
Reported by: TRAINED SPOTTER

Hail in PERKINS, SOUTH DAKOTA
From 21-JUL-05 16:15:00 to 21-JUL-05 16:15:00 (MST)
Location: LODGEPOLE
Magnitude: 1.00 
Property damage: 0
Crop damage: 0
Reported by: TRAINED SPOTTER

Hail in HAAKON, SOUTH DAKOTA
From 21-JUL-05 20:30:00 to 21-JUL-05 20:30:00 (MST)
Location: PHILIP
Magnitude: 0.88 
Property damage: 0
Crop damage: 0
Reported by: GENERAL PUBLIC

Hail in MEADE, SOUTH DAKOTA
From 21-JUL-05 16:05:00 to 21-JUL-05 16:05:00 (MST)
Location: MUD BUTTE
Magnitude: 1.25 
Property damage: 0
Crop damage: 0
Reported by: TRAINED SPOTTER

Thunderstorm Wind in PERKINS, SOUTH DAKOTA
From 21-JUL-05 17:00:00 to 21-JUL-05 17:00:00 (MST)
Location: BISON
Magnitude: 68 MG
Property damage: 0
Crop damage: 0
Reported by: TRAINED SPOTTER

Thunderstorm Wind in PERKINS, SOUTH DAKOTA
From 21-JUL-05 17:00:00 to 21-JUL-05 17:00:00 (MST)
Location: BISON
Magnitude: 70 EG
Property damage: 500K
Crop damage: 0
Reported by: LAW ENFORCEMENT

Many trees were downed, power poles blown over east of town, roofs damaged, and windows of houses and automobiles broken by wind driven hail.

Thunderstorm Wind in PERKINS, SOUTH DAKOTA
From 21-JUL-05 17:00:00 to 21-JUL-05 17:00:00 (MST)
Location: BISON
Magnitude: 61 EG
Property damage: 20K
Crop damage: 0
Reported by: LAW ENFORCEMENT

Machine shed destroyed by wind.

Thunderstorm Wind in MEADE, SOUTH DAKOTA
From 21-JUL-05 18:50:00 to 21-JUL-05 18:50:00 (MST)
Location: HOWES
Magnitude: 52 EG
Property damage: 0
Crop damage: 0
Reported by: TRAINED SPOTTER

Hail in HAAKON, SOUTH DAKOTA
From 21-JUL-05 20:11:00 to 21-JUL-05 20:11:00 (MST)
Location: PHILIP
Magnitude: 1.25 
Property damage: 0
Crop damage: 0
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in PERKINS, SOUTH DAKOTA
From 21-JUL-05 16:30:00 to 21-JUL-05 16:30:00 (MST)
Location: LEMMON
Magnitude: 52 EG
Property damage: 2K
Crop damage: 0
Reported by: GENERAL PUBLIC

Wind driven hail broke windows of 2 automobiles.

Hail in MEADE, SOUTH DAKOTA
From 21-JUL-05 18:35:00 to 21-JUL-05 18:35:00 (MST)
Location: HOWES
Magnitude: 1.00 
Property damage: 0
Crop damage: 0
Reported by: TRAINED SPOTTER

Thunderstorm Wind in PERKINS, SOUTH DAKOTA
From 21-JUL-05 17:10:00 to 21-JUL-05 17:10:00 (MST)
Location: USTA
Magnitude: 52 EG
Property damage: 0
Crop damage: 0
Reported by: TRAINED SPOTTER

Hail in MEADE, SOUTH DAKOTA
From 21-JUL-05 17:56:00 to 21-JUL-05 18:05:00 (MST)
Location: FAITH
Magnitude: 3.00 
Property damage: 0
Crop damage: 0
Reported by: LAW ENFORCEMENT

Lots of nickel sized hail with a few hail stones to 3 inches in diameter.

Hail in ZIEBACH, SOUTH DAKOTA
From 21-JUL-05 18:10:00 to 21-JUL-05 18:10:00 (MST)
Location: RED SCAFFOLD
Magnitude: 1.00 
Property damage: 0
Crop damage: 0
Reported by: TRAINED SPOTTER

Hail in PERKINS, SOUTH DAKOTA
From 21-JUL-05 16:00:00 to 21-JUL-05 16:00:00 (MST)
Location: WHITE BUTTE
Magnitude: 1.00 
Property damage: 0
Crop damage: 0
Reported by: GENERAL PUBLIC